Cleaning compositions for all sorts of purposes create suds or foam. This foaming action is a disadvantage in many contexts as it makes dealing with effluent wash baths difficult and bothersome. The foam can get in the way of the user and obstruct the user's vision of the item being cleaned so that the substrate must be rinsed just to see if it is now clean or needs further treatment, and, in situations where spacing is tight, the foam itself can get in the way of the cleaning solution reaching, cleaning, and rinsing away from the substrate tight spaces. Excessive foam will also cause cavitation of pump systems, greatly reducing the efficiency and effectiveness of spray systems. Excessive foam will also cause sump bath spill over with loss of active cleaning agents. Defoaming is also important in connection with heavy soil baths and in connection with water soluble cutting fluids based on soaps. For these reasons, low foaming cleaning materials and defoamers (to cut or eliminate the foam that is otherwise present) have found wide acceptance and usefulness.
Many different types of compounds have been used for defoaming purposes in different contexts. In general, it has been said that defoamers are "systems related" and that the characteristics of the formulation intended to act as the defoamer, as well as the characteristics of the liquid to be wetted, must be taken into account. Hence, it is extremely difficult to transfer the teachings and experience from one group of agents acting on one foaming system to the same (or another) group of agents acting on another foaming system. See Degussa Technical Bulletin #42, "Synthetic Silicas for Defoamers". This Bulletin also details the use of silica, both hydophobic as well as hydrophilic types, as defoamers.
Silicone oils are also used as defoaming agents and have been found to be extremely effective materials. However, the silicone oils suffer from a major drawback in that they tend to remain on the surface of the parts being cleaned, which can adversely affect post-process operations such as painting, plating, welding, bonding, etc.
Furthermore, once a suitable defoamer has been identified, it must also be formulated for suitable delivery without adversely affecting the defoaming properties. As multiple defoamers are incorporated into a single defoaming product, the ability to adequately and advantageously formulate them into a single product becomes much more difficult. Yet, it is extremely important that when more than one defoamer is to be employed, the various defoamers used, as well as the carrier formulation for them, do not adversely affect one another.
One difficulty is the possible result of multiple phases. When this happens, not all of the defoamers will necessarily reach all of the desired areas. For example, a highly hydrophobic defoamer in combination with a highly hydrophilic defoamer blended together to act on a particular foaming composition will frequently separate into distinctive layers. Attempts to remix these layers during or just before use are frequently ineffective, time consuming, and can be quite costly.
For all these reasons, and many more which are apparent to those of ordinary skill in this art, single phase multiple defoaming agent compositions would be extremely useful, either as separate cleaning aids or as components to be added directly to the cleaners. It is just as useful for the components of such a single phase defoamer to be invcorporated separetly as raw materials into a cleaning product rather than formulating a pre-blend of the multiple defoamers.
Furthermore, when used as part of the cleaning composition, the total elimination of foaming action may be just as undesirable as excess foaming action. Hence, it is critical that the defoamer action be matched carefully with the cleaning composition to which it will be added.